The Rumor Mill tells us that Tor is not looking for NC-17 books — they are seeking straight erotica. While you will find many useful explanations of this distinction, in situation like this, we always turn to the Supreme Court: you’ll know it when you see it.
For those keeping score at home, there are now exactly three New York publishers who have declined to jump on the erotica bandwagon. Their names are changed to protect their stockholders.